1. Field of the Invention
The invention relates to an improved valve cutoff control device. It more particularly relates to an improved seismic safety cutoff device for controlling a valve or an electrical switch during the application of an external force such as an earthquake or an explosion.
2. Description of the Prior Art
Various forms of seismic safety cutoff devices have found extensive use by building safety and construction personnel over the years. The need for automatically shutting off valves or switches, in the event of a natural disaster such as an earthquake, has long existed. But of the known prior art devices each has had various problems or disadvantages in their application, performance, maintenance or construction.
Further examination of the prior art discloses the need for improved devices. Of the known prior art devices, several were even specifically designed as an earthquake safety cutoff device. Most of them were designed to be responsive to forces and motion in all horizontal directions. Many of these devices require the use of tools to reset the apparatus once it has been actuated. Many of the devices could not be reset without shutting off the main control valve in some other location. Only a few could be easily functionally tested after installation. Very few provided any visual indication of the device being in an operable position after installation and most of the devices did not provide for adaptability to existing valve structures. Many of the devices appear to be fragile and were not tamper-resistant. These prior art devices generally were not designed for high reliability, simplicity and low cost. Several of these devices were not independent of the pressure in the line they were to control. And, lastly, none of the devices were practically suitable for use in safety cutoff of electrical switch devices.